WO2001073377A1 - Systeme et procede de juxtaposition pour une source de lumiere a diode-laser pour gyroscope optique - Google Patents
Systeme et procede de juxtaposition pour une source de lumiere a diode-laser pour gyroscope optique Download PDFInfo
- Publication number
- WO2001073377A1 WO2001073377A1 PCT/US2001/009492 US0109492W WO0173377A1 WO 2001073377 A1 WO2001073377 A1 WO 2001073377A1 US 0109492 W US0109492 W US 0109492W WO 0173377 A1 WO0173377 A1 WO 0173377A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- signal
- laser diode
- dithering
- digital
- analog
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/58—Turn-sensitive devices without moving masses
- G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
- G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
- G01C19/721—Details
Definitions
- This invention relates to a system and method for improving the spectrum line width and stability of a laser diode light source and, more specifically, to fiber optic gyroscopes including laser diodes.
- conventional laser diode light sources are economical and readily available commercially.
- Conventional laser diode light sources are widely used in the telecommunication industry and are effective over a wide temperature range.
- a conventional laser diode light source is effective over a temperature range of -30 to 75 degrees Celsius.
- conventional laser diode light sources are generally not applicable to fiber optic gyroscope applications due to their narrow spectrum linewidth and unstable light spectrum characteristics. These attributes cause sub-interferometer effects in the fiber optic gyroscope which result in a poor in-run bias stability and scale factor stability.
- One proposal to mitigate the sub-interferometer effects is to use only the non-lasing operational region of the conventional laser diode as an operational light source for operating the fiber optic gyroscope.
- a drawback of this proposal is that the power level of the non-lasing operational region of the conventional laser diode is very low. Therefore, the angle random walk characteristic of the fiber optic gyroscope tends to be undesirable.
- Other conventional light sources such as super luminescence diode (SLD) and pump light sources, require active temperature controls and are very expensive to operate.
- the invention provides a system and method for improving spectrum linewidth and stability while using the lasing region of a conventional laser diode light source.
- the inventive system and method provide a specially varying signal for varying the drive current of the laser diode light source. By varying the drive current, we have discovered that the spectrum linewidth and stability of the conventional laser diode light source are significantly improved.
- this specially varying signal as a dithering signal by analogy to the technique used in telecommunication, such as television broadcasting, representing the entire gray scale of a picture by picture elements with only one of two levels (“white” and “black”) in which a multilevel input image signal is compared with a position dependent set of thresholds, and picture elements are set to "white” only where the image input signal exceeds the threshold.
- an analog dithering system for generating an analog dithering signal.
- a digital dithering system is provided for generating a digital dithering signal.
- the analog and digital dithering signals can be used in a plurality of applications where a variation of a light source's drive current is warranted, such as in a fiber optic gyroscope.
- the inventive system and method realize an ultra low cost light source that can operate in a wide temperature range, e.g., -30 to 75 degrees Celsius, and requires very low power consumption.
- Figure 1 is a schematic diagram of one illustrative embodiment of our invention.
- Figure 2 is a chart illustrating a typical spectrum of conventional laser diode light source
- Figure 3 is chart illustrating a spectrum of conventional laser diode light source where dithering is performed according to the present invention
- Figure 4 is a block diagram of an analog system for generating a dithering signal for a fiber optic gyroscope illustrative of another specific embodiment of the present invention.
- Figure 5 is a block diagram of a digital system for generating a dithering signal for a fiber optic gyroscope illustrative of a further specific embodiment of the present invention.
- FIG. 1 there is depicted one specific illustrative embodiment of our invention, comprising a fiber optic gyro 10 that can be driven by a light source 11 which is a conventional and inexpensive laser diode.
- the gyro 10 includes a fiber coil 13 and an integrated optics chip 14 which includes a polarizer 15.
- the light source 11 is incorporated in the power control loop 17 which also includes the coupler 19 connected to the light source 11 for transmitting the laser beam to the gyro 10 and also connected to photodiodes 20 which receive the returned light beam from the gyro 10.
- a photodiode 20 is connected through a transimpedance amplifier 21, a variable amplifier/filter 22, and an analog to digital converter to a field programmable gate array 24.
- the field progr-immable gate array 24 creates a dither pattern generated by and under control of a digital signal processor 26.
- the dither signal appears on the output 29 of the array 24 and, after passing through a digital to analog converter 30, is applied through the light source drive circuit 31 to the light source 11.
- the control signal X(n) that appears on lead 29 is given by the following equation
- the array 24 adds the dither and control signal to modulate the light source, as shown in Figure 1, through the gain control loop including the converter 30 and the driver 31. Further, in accordance with our invention, the control loop maintains the light source under various operating conditions that enable the fiber optics gyroscope to use the lasing region of the laser diode and stabilize the modulated light spectrum bandwidth.
- the amount of photons emitted from a conventional laser diode light source depends on the drive current injected into the laser diode light source. Beyond the lasing threshold, light power emitted by the laser diode light source is almost linearly proportional to the supplied drive current until the light power reaches saturation.
- Figure 2 plots the spectrum as a function of power (uW) and wavelength (urn) for a conventional laser diode with a standard drive current applied. It is noted that the spectrum is obtained by four snap shots using a spectrum analyzer. The spectrum variation from one snap shot to the next can be easily observed. The amount of protons emitted from a laser diode depends on the device current injected into the laser diode. Beyond the lasing threshold, light power emitted by the laser diode is almost linearly proportional to the supplied current until it reaches saturation. A typical spectrum generated by such a laser diode is depicted in Figure 2.
- the estimated wavelength variation factor is the ratio of the standard deviation to the average.
- the ratio is expressed in terms of parts per million (ppm) and it is an indication of scale factor stability.
- the amplitude and frequency of the dithering signal affect the effectiveness of the dithering method with respect to varying light sources. Therefore, a dithering signal having specific characteristics is advantageously provided to optimally stabilize and improve linewidth of a laser diode spectrum of a particular light source.
- the wave-shape of the dithering signal does not affect the effectiveness of the dithering method of the present invention. Accordingly, the wave-shape of the dithering signal can be any shape, including pseudo random noise, white noise, square, sinusoidal, triangular, and combinations thereof.
- the dithering method of the present invention can be implemented efficiently using either analog or digital systems to generate the dithering signal. These systems can be used to adjust several characteristics of the generated dithering signal, such as amplitude, frequency, phase and waveform. While one specific technique for generating the dither signals for driving a laser diode is depicted in the specific illustrative embodiment of Figure 1, other dither signal drive systems, either analog or digital, can be employed, as discussed below with reference to the embodiments depicted in Figures 4 and 5.
- Figure 4 illustrates a block diagram of an analog system for generating a dithering signal according to the present invention for a fiber optic gyroscope.
- the analog system is designated generally by reference numeral 300 and includes a function generator 302, a laser diode digital-to-analog converter (DAC) 304, a laser diode drive circuit 306, an adder 308, and an amplifier 310.
- a digital signal processor (DSP) 312 is also included to generate a dc level signal as required by the laser diode. The dc level signal controls the emitted power from the laser diode.
- the function generator 302 can generate several different waveforms, such as square, sinusoidal and triangular. It is contemplated that the function generator 302 can also generate a signal having a waveform which is a combination of the above-mentioned waveforms. The function generator 302 can also generate signals having noise, such as pseudo random noise and/or white noise.
- the function generator 302 is turned on and a particular waveform or signal type, e.g., a signal having pseudo random and/or white noise, is selected using control knobs, buttons and/or switches. Accordingly, the function generator 302 generates an analog function signal having the selected waveform or signal type.
- the analog function signal is transmitted to the adder 308.
- the DAC 304 is also turned on for converting the dc level signal received from the DSP 312 to an analog signal.
- the analog signal is transmitted to the laser diode drive circuit 306 causing the laser diode drive circuit 306 to generate a current drive signal.
- the function of the laser diode drive circuit 306 is to convert the input voltage level to the current level as required by the laser diode.
- impedance matching and amplification circuitry can be included in the laser diode drive circuit 306.
- the current drive signal is transmitted to the adder 308.
- the adder 308 adds the analog function signal, i.e., the signal generated by the function generator 302, and the current drive signal, i.e., the signal generated by the laser diode drive circuit 306, to provide an analog dithering signal.
- the analog dithering signal is transmitted to the amplifier 310 which amplifies the analog drive signal including the variations caused by the dithering signal, before transmitting the dithered analog drive signal to the laser diode light source of the fiber optic gyro.
- the amplitude, frequency and/or phase of the analog function signal can be adjusted during operation of the system 300 using control knobs, buttons and/or switches on the function generator 302 to adjust the amplitude, frequency and/or phase of the generated dithering signal to provide minimum coherence length of the laser diode light source. It is contemplated that the function generator 302 can be programmed with a set of instructions to automatically adjust the amplitude, frequency and/or phase of the analog function signal. With reference to Figure 5, there is shown a block diagram of a digital system for generating the dithering signal for use according to a further illustrative embodiment of the present invention.
- the digital system is designated generally by reference numeral 400 and includes a digital signal processor (DSP) 402, a digital-to-analog converter (DAC) 404, and an amplifier 406.
- DSP digital signal processor
- DAC digital-to-analog converter
- the DSP 402 is turned on and a particular waveform is selected either automatically or manually via a control panel.
- the waveform can be selected from a group which includes at least square, sinusoidal, triangular, and combinations thereof. Accordingly, the DSP 402 generates a digital function signal having the selected waveform.
- the digital function signal is transmitted to the DAC 404 which converts the digital function signal to an analog dithering signal.
- the analog dithering signal is then amplified by the amplifier 406 before it is transmitted to the laser diode light source.
- the DSP 402 of the digital system 400 can be programmed with a set of instructions to automatically control the characteristics of the generated digital function signal. That is, the amplitude, frequency and/or phase of the generated digital function signal can be automatically adjusted, which in turn causes the adjustment of the amplitude, frequency and/or phase of the dithering signal to provide minimum coherence length of the laser diode light source. It is contemplated that the DSP 402 can also be manually controlled via a control panel for adjusting the characteristics of the generated digital function signal.
- the analog system 300 of Figure 4 and the digital system 400 of Figure 5 provide a dithered drive signal having an amplitude of approximately four volts and a frequency of approximately 40 kHz.
- our invention provides a system and method for improving spectrum linewidth and stability while using the lasing region of a conventional laser diode light source, and more specifically provides for an improved fiber optic gyroscope using a conventional laser diode as its light source.
- Our inventive system and method, as described above, provide a dithering signal for varying the drive current of the laser diode light source.
- the exact wave shape of the dithering signal does not affect the stability of the spectrum significantly, we have found that some commonly used available signal patterns, such as pseudo random noise, square wave, and sinusoidal wave, are both useful and practical for employment with the gyroscope.
- some commonly used available signal patterns such as pseudo random noise, square wave, and sinusoidal wave, are both useful and practical for employment with the gyroscope.
- the spectrum linewidth and stability of the conventional laser diode light source are significantly improved, so that the conventional laser diode can be employed as the light source for a fiber optic gyroscope.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Optics & Photonics (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Gyroscopes (AREA)
Abstract
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP01922649A EP1409960A4 (fr) | 2000-03-27 | 2001-03-23 | Systeme et procede de juxtaposition pour une source de lumiere a diode-laser pour gyroscope optique |
CA002404465A CA2404465A1 (fr) | 2000-03-27 | 2001-03-23 | Systeme et procede de juxtaposition pour une source de lumiere a diode-laser pour gyroscope optique |
JP2001571052A JP2005515401A (ja) | 2000-03-27 | 2001-03-23 | 光学ジャイロスコープ用のレーザ・ダイオード光源のディザリング・システムおよび方法 |
BRPI0109668-0A BR0109668A (pt) | 2000-03-27 | 2001-03-23 | giroscópio de fibra ótica, processo e sistema para aperfeiçoar a estabilidade e a largura de linha do espectro de um diodo a laser e processo para aplicação de luz de um diodo a laser a um giro de fibra ótica |
AU2001249426A AU2001249426A1 (en) | 2000-03-27 | 2001-03-23 | Dithering system and method for a laser diode light source for an optical gyroscope |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US19227600P | 2000-03-27 | 2000-03-27 | |
US60/192,276 | 2000-03-27 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001073377A1 true WO2001073377A1 (fr) | 2001-10-04 |
Family
ID=22709005
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2001/009492 WO2001073377A1 (fr) | 2000-03-27 | 2001-03-23 | Systeme et procede de juxtaposition pour une source de lumiere a diode-laser pour gyroscope optique |
Country Status (7)
Country | Link |
---|---|
US (1) | US6657729B2 (fr) |
EP (1) | EP1409960A4 (fr) |
JP (1) | JP2005515401A (fr) |
AU (1) | AU2001249426A1 (fr) |
BR (1) | BR0109668A (fr) |
CA (1) | CA2404465A1 (fr) |
WO (1) | WO2001073377A1 (fr) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10138154A1 (de) * | 2001-08-03 | 2003-02-27 | Litef Gmbh | Verfahren und Einrichtung zur Erhöhung der Langzeit-Betriebszuverlässigkeit eines faseroptischen Interferometers |
EP1439644A1 (fr) * | 2003-01-14 | 2004-07-21 | Agilent Technologies, Inc. - a Delaware corporation - | Procédé et dispositif à injecter une tonalité pilote dans un signal numérique |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7468998B2 (en) * | 2005-03-25 | 2008-12-23 | Pavilion Integration Corporation | Radio frequency modulation of variable degree and automatic power control using external photodiode sensor for low-noise lasers of various wavelengths |
JP5643584B2 (ja) * | 2010-09-13 | 2014-12-17 | 日本航空電子工業株式会社 | リングレーザジャイロ装置 |
US8213018B2 (en) | 2010-11-10 | 2012-07-03 | Honeywell International Inc. | Constant optical power sensor using a light source current servo combined with digital demodulation intensity suppression for radiation and vibration insensitivity in a fiber optic gyroscope |
US8873063B2 (en) | 2012-08-14 | 2014-10-28 | Honeywell International Inc. | Low noise resonator fiber optic gyro |
CN106323339A (zh) * | 2016-08-23 | 2017-01-11 | 中国航空工业集团公司西安飞行自动控制研究所 | 一种低强度噪声微小型闭环光纤陀螺的制造方法 |
CN112284411B (zh) * | 2020-09-09 | 2023-07-28 | 北京航天时代激光导航技术有限责任公司 | 一种激光惯组的抖动控制方法 |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5136600A (en) * | 1990-09-18 | 1992-08-04 | Litton Systems Inc. | Stabilization apparatus and method for an sfs |
US6215809B1 (en) * | 1996-03-25 | 2001-04-10 | Sdl, Inc. | Stabilization of laser sources with closely-coupled optical reflectors using an internal dither circuit |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4034664A1 (de) * | 1990-10-31 | 1992-05-07 | Litef Gmbh | Faseroptisches sagnac-interferometer zur drehratenmessung |
DE4037118C1 (fr) * | 1990-11-22 | 1992-04-30 | Messerschmitt-Boelkow-Blohm Gmbh, 8012 Ottobrunn, De | |
US5329396A (en) * | 1992-10-28 | 1994-07-12 | At&T Bell Laboratories | Reduction of stimulated brillouin scattering in a fiber optic transmission system |
FR2700895B1 (fr) * | 1993-01-28 | 1995-03-03 | Jean Debeau | Procédé et dispositif de génération d'impulsions optiques. |
JP3259862B2 (ja) * | 1993-02-18 | 2002-02-25 | 日本電信電話株式会社 | 光信号送信器 |
US5477368A (en) * | 1994-12-29 | 1995-12-19 | At&T Corp. | High power lightwave transmitter using highly saturated amplifier for residual AM suppression |
US5563705A (en) * | 1995-06-07 | 1996-10-08 | Honeywell, Inc. | Optical power balancing in interferometric fiber optic gyroscopes |
JPH1096634A (ja) * | 1996-09-24 | 1998-04-14 | Hitachi Ltd | 位相変調式光ファイバジャイロ |
JP3269980B2 (ja) * | 1997-01-13 | 2002-04-02 | 沖電気工業株式会社 | 光送信器 |
US5991061A (en) * | 1997-10-20 | 1999-11-23 | Lucent Technologies Inc. | Laser transmitter for reduced SBS |
US6359918B1 (en) * | 1998-06-30 | 2002-03-19 | Honeywell International Inc. | Light source control device |
-
2001
- 2001-03-22 US US09/814,902 patent/US6657729B2/en not_active Expired - Fee Related
- 2001-03-23 AU AU2001249426A patent/AU2001249426A1/en not_active Abandoned
- 2001-03-23 CA CA002404465A patent/CA2404465A1/fr not_active Abandoned
- 2001-03-23 JP JP2001571052A patent/JP2005515401A/ja active Pending
- 2001-03-23 BR BRPI0109668-0A patent/BR0109668A/pt not_active IP Right Cessation
- 2001-03-23 WO PCT/US2001/009492 patent/WO2001073377A1/fr not_active Application Discontinuation
- 2001-03-23 EP EP01922649A patent/EP1409960A4/fr not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5136600A (en) * | 1990-09-18 | 1992-08-04 | Litton Systems Inc. | Stabilization apparatus and method for an sfs |
US6215809B1 (en) * | 1996-03-25 | 2001-04-10 | Sdl, Inc. | Stabilization of laser sources with closely-coupled optical reflectors using an internal dither circuit |
Non-Patent Citations (1)
Title |
---|
See also references of EP1409960A4 * |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10138154A1 (de) * | 2001-08-03 | 2003-02-27 | Litef Gmbh | Verfahren und Einrichtung zur Erhöhung der Langzeit-Betriebszuverlässigkeit eines faseroptischen Interferometers |
DE10138154C2 (de) * | 2001-08-03 | 2003-06-05 | Litef Gmbh | Verfahren und Einrichtung zur Erhöhung der Langzeit-Betriebszuverlässigkeit eines faseroptischen Interferometers |
US7173712B2 (en) | 2001-08-03 | 2007-02-06 | Litef Gmbh | Method and device for increasing the long-term operational reliability of a fiber optic interferometer |
EP1439644A1 (fr) * | 2003-01-14 | 2004-07-21 | Agilent Technologies, Inc. - a Delaware corporation - | Procédé et dispositif à injecter une tonalité pilote dans un signal numérique |
US7313326B2 (en) | 2003-01-14 | 2007-12-25 | Avago Technologies Fiber Ip ( Singapore) Pte Ltd. | Method to inject pilot tone into microcontroller-supervised DWDM transmitters |
Also Published As
Publication number | Publication date |
---|---|
US20030189710A1 (en) | 2003-10-09 |
BR0109668A (pt) | 2006-10-10 |
CA2404465A1 (fr) | 2001-10-04 |
AU2001249426A1 (en) | 2001-10-08 |
JP2005515401A (ja) | 2005-05-26 |
EP1409960A1 (fr) | 2004-04-21 |
EP1409960A4 (fr) | 2009-12-30 |
US6657729B2 (en) | 2003-12-02 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5579328A (en) | Digital control of laser diode power levels | |
JP2932100B2 (ja) | レーザダイオード制御回路 | |
US4292606A (en) | Modulation current control of laser diodes | |
JP3405046B2 (ja) | レーザ光発生装置 | |
JP3459081B2 (ja) | 外部キャビティレーザ | |
EP0911930A1 (fr) | Source de lumière à bande large | |
KR20150145803A (ko) | 펄스 레이저 생성기 및 생성 방법 | |
US7379672B2 (en) | Photonic RF distribution system | |
JPH0118589B2 (fr) | ||
US5544183A (en) | Variable wavelength light source | |
GB2025121A (en) | Improvements in or relating to the stabilisation of injection lasers | |
EP0858138A3 (fr) | Stabilisation de la longueur d'onde dans les lasers à semiconducteur accordables | |
EP0630083B1 (fr) | Dispositif de modulation et amplification optique avec rapport signal/bruit élevé | |
US6657729B2 (en) | Dithering system and method for a laser diode light source for an optical gyroscope | |
US6751014B2 (en) | Automatic gain control and dynamic equalization of erbium doped optical amplifiers in wavelength multiplexing networks | |
JP3441938B2 (ja) | 光パルス発生器 | |
US6370170B1 (en) | Laser frequency stabilization apparatus | |
US6721089B1 (en) | Method and apparatus for expanding the dynamic range of optical amplifiers | |
US6137814A (en) | Light emitting device having an integrated component including at least one laser section and at least one modulation section | |
GB2278230A (en) | Optical amplifier | |
JPH09246646A (ja) | 半導体レーザ制御装置 | |
US20040105470A1 (en) | Method for reducing non-linearities in a laser communication system | |
JPH09500759A (ja) | 高出力レーザ増幅器 | |
EP0613262B1 (fr) | Source de bruit optique | |
JPH0560695B2 (fr) |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG UZ VN YU ZA ZW |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
REG | Reference to national code |
Ref country code: DE Ref legal event code: 8642 |
|
ENP | Entry into the national phase |
Ref country code: JP Ref document number: 2001 571052 Kind code of ref document: A Format of ref document f/p: F |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1020027012881 Country of ref document: KR Ref document number: 2404465 Country of ref document: CA |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2001922649 Country of ref document: EP |
|
WWP | Wipo information: published in national office |
Ref document number: 2001922649 Country of ref document: EP |
|
WWW | Wipo information: withdrawn in national office |
Ref document number: 1020027012881 Country of ref document: KR |
|
ENP | Entry into the national phase |
Ref document number: PI0109668 Country of ref document: BR |